Heart valve

ABSTRACT

A heart valve includes a valve body made of a flexible material such as pericardium. The valve body is made of two layers of material, an outer layer, and an inner layer that defines a plurality of leaflets. The leaflets of the inner layer are attached to the outer layer. In some embodiments the valve body is made by cutting a single piece of flat source tissue, folding the cut tissue and forming it into a tubular pattern having the inner and outer layers. The multi-layer valve body can be mounted on a stent for delivery within a patient&#39;s heart.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/747,327, filed Jan. 22, 2013, which is a continuation of U.S.application Ser. No. 12/569,856, filed Sep. 29, 2009, now U.S. Pat. No.8,403,983, which claims priority to U.S. Provisional Application No.61/136,716, which was filed on Sep. 29, 2008. U.S. application Ser. Nos.13/747,327 and 12/569,856, are each incorporated by reference herein inits entirety and are to be considered a part of this specification.Concerning Provisional Application No. 61/136,716, at least the portionsdescribing embodiments of a tissue-based valve body formed from flatsource material, manufacturing of same, and placement upon and use inconjunction with a stent, as discussed in paragraphs [00020]-[00027] andFIGS. 1A-8D are hereby incorporated by reference.

BACKGROUND

1. Field of the Invention

The present invention relates to replacement heart valves. Morespecifically, the invention relates to tissue- or simulated tissue-basedreplacement heart valves.

2. Description of the Related Art

Human heart valves, which include the aortic, pulmonary, mitral andtricuspid valves, function essentially as one-way valves operating insynchronization with the pumping heart. The valves allow blood to flowin a downstream direction, but block blood from flowing in an upstreamdirection. Diseased heart valves exhibit impairments such as narrowingof the valve or regurgitation. Such impairments reduce the heart'sblood-pumping efficiency and can be a debilitating and life threateningcondition. For example, valve insufficiency can lead to conditions suchas heart hypertrophy and dilation of the ventricle. Thus, extensiveefforts have been made to develop methods and apparatus to repair orreplace impaired heart valves.

Prostheses exist to correct problems associated with impaired heartvalves. For example, mechanical and tissue-based heart valve prosthesescan be used to replace impaired native heart valves. More recently,substantial effort has been dedicated to developing replacement heartvalves, particularly tissue-based replacement heart valves that can bedelivered with less trauma to the patient than through open heartsurgery. Replacement valves are being designed to be delivered throughminimally invasive procedures and even percutaneous procedures. Suchreplacement valves often include a tissue-based valve body that isconnected to an expandable stent that is then delivered to the nativevalve's annulus.

Development of replacement heart valves that can be compacted fordelivery and then controllably expanded for controlled placement hasproven to be particularly challenging. Further, durability concerns,particularly with tissue-based replacement valves, are at the forefront.For example, tissue-based valves typically include components that aresewn together, and such seams can be sources of stress concentrations,particularly when relatively thin tissue is used.

SUMMARY

Accordingly, there is in the need of the art for a tissue-based heartvalve with enhanced durability and which lends itself to compaction andcontrolled expansion in a minimally invasive and/or percutaneousdelivery.

In accordance with one embodiment, the present invention provides areplacement heart valve that comprises a valve body having an outerlayer and an inner layer. The outer layer is tubular and has alongitudinal axis, an upstream end and a downstream end, and is formedfrom a thin, flexible material. The inner layer is generally tubular,has a longitudinal axis generally collinear with the outer layer, and ispositioned within the tubular outer layer. The inner layer is formedfrom a thin, flexible material and defines a plurality of leafletsadapted to move between an open state and a coapted state. Each leaflethas a side edge and a downstream portion. Adjacent leaflets of the innerlayer are connected by a commissural portion. The leaflets are attachedto the outer layer along the leaflet side edges, and the commissuralportions are attached to the outer layer downstream of at least aportion of the leaflet side edges;

In one such embodiment, the inner and outer layers are constructed froma single, contiguous section of the flexible material. In anotherembodiment, the inner and outer layers are folded relative to oneanother at the upstream end so that the inner layer is contiguous withthe outer layer at the upstream end.

In another embodiment, the outer layer comprises a commissural slit, andan edge of one of the commissural portions of the inner layer extends atleast partially through the slit. In one such embodiment, the outerlayer comprises a leaflet slit shaped to complement a correspondingleaflet side edge, and the leaflet side edge extends at least partiallythrough the slit.

In yet another embodiment, the outer layer has a plurality of windowsformed therethrough, and the windows are configured so that, when theleaflets are in the coapted state, blood readily flows through thewindows.

In a further embodiment, a replacement heart valve comprises a valvebody and an elongate stent that can be radially compacted to a compactedstate and radially expanded to an expanded state. The stent having alongitudinal axis and the valve body is attached to the stent.

In one such embodiment, an outer layer of the valve body is on an outerside of the stent and an inner layer of the valve body is on an innerside of the stent so that the stent is sandwiched between the inner andouter layers.

In another such embodiment, the valve body is positioned so that thestent is adjacent an outer surface of the valve body. In some suchembodiments, an outer layer of the valve body is connected to the stent,and an inner layer of the valve body is directly connected to the outerlayer, but is not directly connected to the stent. In additional suchembodiments, when the leaflets are in an open position, an outer layerof the valve body is interposed between open leaflets and the stent.

In yet another such embodiment, the stent has a foreshortening portion,which foreshortening portion is configured so that as the stent isradially compacted, the foreshortening portion longitudinally expands,and as the stent is radially expanded, the foreshortening portionlongitudinally contracts.

In one embodiment with such a foreshortening stent, at least a portionof the valve body is disposed at least partially within theforeshortening portion, and the valve body is attached to the stent atone or more connecting points, which connecting points are generallyaligned with an axial point along the stent longitudinal axis, so thatduring foreshortening the stent longitudinally moves relative to thevalve body without longitudinally stretching or crushing the valve body.One such embodiment additionally comprises a longitudinally expandablematerial that is directly connected to the stent and to the valve body.The flexible material is directly connected to the stent at one or moreconnection points that are longitudinally spaced from the axial point.

In another embodiment having a foreshortening stent, the stentadditionally comprises a non-foreshortening portion, and a valve body ismaintained within the non-foreshortening portion.

In accordance with another embodiment, the present invention provides amethod of making a replacement heart valve. The method includesproviding a flat, flexible source material and cutting the flat materialaccording to a desired pattern. The pattern defines first and secondpattern ends, a skirt portion, and a leaflet portion. The leafletportion defines a plurality of leaflets, commissures extending betweenadjacent leaflets, and each leaflet having side edges. The methodadditionally comprises adjoining the first and second pattern ends so asto form the flat material into a tube, folding the leaflet portionrelative to the skirt portion along a fold line so that the leafletportion is generally within the skirt portion, attaching the commissuresto the skirt portion, and attaching the leaflet side edges to the skirtportion.

Another embodiment additionally comprises providing a form having ashape that is substantially the negative of a desired shape of the valvein a closed state, the form having leaflet shaping portions, and afterthe flat material has been formed into a tube and the commissuresattached to the skirt portion, placing the valve upon the form so thatthe leaflets engage the leaflet shaping portions, and attaching theleaflet side edges to the skirt portion when the leaflets are engagedwith the leaflet shaping portions.

A further such embodiment additionally comprises forming leaflet slitsin the skirt portion, the leaflet slits generally corresponding the adesired curvature of the leaflets, and placing the valve upon the formso that the leaflets engage the leaflet shaping portions comprisesextending the leaflet side edges through the leaflet slits in the skirtportion.

Another embodiment additionally comprises providing an elongate stent,and attaching the skirt portion to the stent.

In accordance with still another embodiment, a method of treating valveinsufficiency of a patient by delivering a replacement heart valve isprovided. The method comprises providing a replacement heart valvecomprising a valve body attached to a stent, the valve body having anupstream end and a plurality of leaflets adapted to open and close, theleaflets each having a downstream portion, the stent being elongate andhaving an upstream end, a downstream end, and a longitudinal midpointhalfway between the upstream and downstream ends, the stent having anannulus attachment zone adapted to engage a native valve annulus, theannulus attachment zone disposed at or adjacent the downstream end ofthe stent, and positioning the heart valve within a patient's heart sothat the annulus attachment zone of the stent engages a patient's mitralannulus, and the longitudinal midpoint of the stent is disposed withinthe patient's left atrium.

In one such embodiment, the step of positioning the heart valvecomprises positioning the valve so that substantially all of the stentis disposed in the patient's mitral annulus or left atrium.

In another embodiment, the valve body is connected to the stent so thatthe leaflets are substantially within the left atrium. In otherembodiments, the valve body is connected to the stent so that thedownstream ends of the leaflets are disposed generally within the mitralannulus.

In accordance with yet another embodiment, the present inventionprovides a flexible tubular valve body defining a plurality of leafletsconnected to a longitudinally stretchable portion. The valve body isless longitudinally stretchable than the longitudinally stretchableportion. In one such embodiment, the valve body and connectedlongitudinally stretchable portion are mounted on a stent that has aforeshortening portion, and a portion of the valve body overlaps theforeshortening portion so the when the stent foreshortens, thelongitudinally stretchable portion preferentially stretches or contractsso that the valve body moves longitudinally relative to the stent.

In another embodiment, a valve body having an inner layer and an outerlayer, the inner layer defining a plurality of leaflets, is constructedby separately forming the inner and outer layers, attaching an upstreamend of the inner layer to the outer layer, and attaching side edges andcommissural tabs of the leaflets to the outer layer. In one suchembodiment, slits are formed through the outer layer, and one or more ofthe commissural tabs and leaflets are drawn at least partially throughcorresponding slits and then secured to the outer layer.

Other inventive embodiments and features are disclosed below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a flat pattern for cutting a flat source material tocreate an embodiment of a heart valve body.

FIG. 2A is a side view of tissue cut according to the flat pattern ofFIG. 1 and formed into a tube.

FIG. 2B is a perspective view of the assembly of FIG. 2A.

FIG. 3A is a perspective view of the assembly of FIG. 1 formed into aheart valve body and shown in an open position.

FIG. 3B shows the heart valve body of FIG. 3A in a closed condition andviewed from a downstream position.

FIG. 3C shows the heart valve body of FIG. 3A in a closed condition andviewed from an upstream position.

FIG. 4A is a schematic view of an embodiment of a stent frame, shown ina compacted state.

FIG. 4B shows the stent frame of FIG. 4A in an expanded state.

FIG. 5 is a side view of the stent frame of FIGS. 4A and B with thevalve body of FIGS. 1-3 mounted thereon.

FIG. 6A is a side perspective view of another embodiment of a heartvalve comprising a tissue valve body mounted on a stent frame.

FIG. 6B shows the heart valve of FIG. 6A in a closed condition andviewed from a downstream position.

FIG. 6C shows the heart valve of FIG. 6A in a closed condition andviewed from an upstream position.

FIG. 7 shows a flat pattern for cutting a flat source tissue to formanother embodiment of a valve body.

FIG. 8 shows a perspective view of a valve body constructed of tissuecut according to the pattern of FIG. 7.

FIG. 9A is a close-up view of a side of the valve body of FIG. 8.

FIG. 9B is a close-up view as in FIG. 9B but showing features of anotherembodiment.

FIG. 10 shows a flat pattern for cutting a flat source tissue to formyet another embodiment of a heart valve body.

FIG. 11 is a schematic side view of another embodiment of a stent framefor supporting a heart valve body.

FIG. 12 is a perspective view of the stent frame of FIG. 11 with a heartvalve body constructed from source tissue cut in accordance with thepattern of FIG. 10 mounted thereon.

FIG. 13 shows the heart valve of FIG. 12 in a closed condition andviewed from a downstream position.

FIG. 14 shows the heart valve of FIG. 12 placed in a mitral annulus of ahuman heart in accordance with one embodiment.

FIG. 15 is a schematic side section view showing opposing walls of aheart valve stent frame similar to that of FIG. 11 and schematicallyshowing placement of an expandable fabric portion on the stent inaccordance with another embodiment.

FIG. 16A is a side view of another embodiment of a heart valve, showingthe valve body of FIG. 8 mounted onto a stent in accordance with anotherembodiment.

FIG. 16B is a side view of the assembly of FIG. 16A shown in a compactedstate.

FIG. 17 shows the heart valve of FIG. 16 placed in a mitral annulus of ahuman heart in accordance with another embodiment.

FIG. 18 shows a flat pattern for cutting a flat source tissue to formyet another embodiment of a valve body.

FIG. 19 depicts a perspective view of a heart valve body constructedfrom the pattern of FIG. 18.

FIG. 20 is a perspective view of an embodiment of a tool forconstructing a tissue valve body.

FIG. 21 shows the tool of FIG. 20 being used to construct a tissue valvebody as in FIG. 18-19.

FIG. 22 shows a flat pattern for cutting a flat source tissue to formanother embodiment of a valve body.

FIG. 23 is a perspective view of an embodiment of a heart valve having avalve body constructed from the pattern of FIG. 22 mounted on a stent.

FIG. 24 is a partial side view of a stent for use in accordance with theassembly of FIG. 23.

FIG. 25 is a schematic partial side view of a vertical cross-section ofthe heart valve of FIG. 24.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present specification and drawings disclose aspects and features ofthe invention in the context of several embodiments of replacement heartvalves and portions thereof that are configured for replacement ofnatural heart valves in a patient. These embodiments may be discussed inconnection with replacing specific valves such as the patient's aorticor mitral valve. However, it is to be understood that the context of aparticular valve or particular features of a valve should not be takenas limiting, and features of any one embodiment discussed herein can becombined with features of other embodiments as desired and whenappropriate.

With initial reference to FIGS. 1-3, a structure for a heart valve body30, along with methods of making the valve body 30, are described. Inthis embodiment, the heart valve body is constructed of a tissue-basedmedia such as bovine pericardium. Of course, other materials such asequine and porcine pericardium, vascular tissue, as well as othernatural and manmade materials that are thin, flexible and durable, maybe employed. Preferably, the tissue is provided as a flat sourcematerial.

FIG. 1 illustrates a flat pattern 32 for cutting flat source tissue toform an embodiment of a heart valve body 30. More specifically, sourcetissue preferably is laid out in a flat format, and then cut accordingto the illustrated flat pattern 32. Preferably the tissue is cut by alaser, but other cutting modes and methods can be employed.

As illustrated in FIG. 1, the flat source tissue cut according to thepattern has first and second pattern ends 34, 36. A skirt portion 40 anda leaflet portion 50 are separated by a fold line 52. The illustratedleaflet portion 50 comprises three leaflets 54 connected to one anotherat commissural tab portions 60. Each leaflet 54 has a downstream edge 62that preferably is curved, and also has curved, generally-opposing firstand second leaflet side edges 64, 66. In accordance with the pattern 32in the illustrated embodiment, the adjacent leaflets 54 are defined byvoids 68 cut between them.

The illustrated skirt portion 40 comprises three windows 70 that aredefined by apertures cut through the flat source tissue. The windows 70each have first and second side edges 72, 74, which first and secondwindow side edges 72, 74 are generally complementary in curvature to thefirst and second side edges 64, 66, respectively, of the correspondingleaflets 54. A downstream ring 76 of the skirt portion 40 preferablyruns continuously from the first pattern end 34 to the second patternend 36. Similarly, an upstream ring portion 78 of the flat pattern 32runs continuously from the first pattern end 34 to the second patternend 36 at and adjacent the fold line 52. Leaflet supports 80 are definedbetween adjacent windows 70, and share the first and second window sideedges 72, 74. The leaflet supports 80 extend from the upstream ring 78to the downstream ring 76. In the illustrated embodiment, the first andsecond pattern ends 34, 36 are arranged to evenly split one of theleaflet supports 80 of the skirt portion 40 and one of the commissuraltab portions 60 of the leaflet portion 50.

With reference to FIGS. 2A and 2B, once the pattern 32 has been cut fromthe flat source tissue, the cut tissue is rolled and the first andsecond pattern ends 34, 36 are joined together to create a tubularstructure as shown. In the illustrated embodiment, the first and secondpattern ends 34, 36 are joined together by a seam that preferablyemploys a conventional suture material. As such, a seam 82 in the skirtportion 40 connects the first and second pattern ends 34, 36 so as tocomplete the leaflet support 80, and a seam 84 in the leaflet portion 50completes the commissural tab 6.

Although sutures are used in the illustrated embodiment, it is to beunderstood that other methods and apparatus can be used to join thefirst and second ends and to make other connections when forming valvebodies. For example, in other embodiments, adhesives, clips or the likemay be employed.

With additional reference to FIGS. 3A-C, once the first and secondpattern ends 34, 36 are joined so as to create a tubular structure, theleaflet portion 50 can then be folded about the fold line 52 andinverted into the interior of the skirt portion 40. As such, the leafletportion 50 of the valve body 30 sits within and generally abutting theskirt portion 40.

With continued reference to FIGS. 3A-C, once folded so that the leafletportion 50 is within the skirt portion 40, the leaflet and skirtportions 50, 40 are attached to one another. More specifically, thefirst and second leaflet edges 64, 66 are attached to the respectivefirst and second window side edges 72, 74 of corresponding leafletsupports 80. As shown, the edges 64, 66, 72, 74 preferably generallyalign so as to be conducive to being connected by a seam. Further, thecommissural tabs 60 are attached to the downstream ring 76 of the skirtportion 40. Preferably, such attachments are accomplished throughstitching in a conventional manner using conventional materials such assuture material. However, other materials, such as adhesives, may alsobe used. Additionally, in some embodiments, the commissural tabs can besecured to the skirt by a clip in lieu of or in addition to a stitching.Also, in still further embodiments, the leaflet and skirt portions canbe formed separately and then connected at, for example, an upstreamring. Such an alternative will apply to other embodiments and featuresdiscussed herein.

Once the leaflet portion 50 has been appropriately connected to theskirt portion 40, the valve body 30 can move between the open conditiondepicted in FIG. 3A to the closed condition depicted in FIGS. 3B and 3C.As shown in FIGS. 3B and 3C, when closed, the valve leaflets 54 coaptwith one another so as to block blood from flowing upstream between theleaflets 54. Also, since the leaflets 54 are sewn securely onto theskirt 40 at the supports 80, no blood will flow between the skirtportion 40 and leaflet portion 50 at the upstream end 78 of the valvebody 30, thus preventing paravalvular leaks. In the illustratedembodiment, the windows 70 of the skirt portion 40 generally align withthe leaflets 54. As such, when the leaflets 54 are in the closedcondition, blood flow is deflected by the leaflets 54 and readily flowsthrough the windows 70.

The valve body 30 of FIGS. 3A-C is appropriate to use to replace apatient's native valve and embodiments employing features described inconnection with the illustrated valve body 30 can be used alone or inconjunction with a stent frame. For example, in one embodiment, a valvebody 30 as in FIG. 3A can be installed into the annulus of a patient'snative aortic valve. In such an embodiment, the upstream ring 78 is sewnor otherwise attached to the native valve annulus, and the downstreamring 76 is attached to the aorta downstream of the annulus. As such, thevalve body 30 sits in the aortic sinus. In this embodiment, the windows70 of the skirt portion 40 are particularly useful in that when theleaflets 54 coapt, blood readily flows through the windows 70 and intothe cardiac arteries that branch off of the aortic sinus.

With reference next to FIGS. 4 and 5, a heart valve body 30 as in FIG. 3can be mounted onto a stent 90. Such a stent can be of various designsand characteristics. For example, such a stent may be self-expandable,balloon-expandable, a hybrid, or the like.

With particular reference to FIGS. 4A and 4B, the illustrated stentframe 90 embodiment supports the valve body 30 and can be expanded froma compacted state as shown in FIG. 4A to an expanded state as shown inFIG. 4B. The illustrated stent 90 preferably is a self-expanding stentconstructed of a flexible material, preferably a shape memory materialsuch as nitinol. As it is self-expanding, the stent 90 is in a fullyopened state, as depicted in FIG. 4B, when relaxed. The illustratedstent 90 preferably is elongate from a first end 92 to a second end 94and is tubular with a longitudinal axis 96 and a generally circularcross section. It is to be understood that in other embodiments stentscan have a non-circular cross section, such as a D-shape, an oval or anotherwise ovoid cross-sectional shape. In the illustrated embodiment aplurality of spaced apart eyelets 98 are provided both at the first end92 and at the second end 94 of the stent frame 90. Other embodiments maybe constructed without such eyelets 98.

The illustrated stent frame 90 has a non-foreshortening portion 100 anda foreshortening portion 110. The portions are joined at a transition112 between the first and second ends 92, 94. Foreshortening refers to abehavior in which the length of the stent 90 in the foreshorteningportion 110 decreases as the radius of the stent increases from thecompacted state to the expanded, deployed state. As such, in FIG. 4A,which shows the stent frame 90 in a compacted state, the foreshorteningportion 110 of the stent frame 90 is longer than when the stent is inthe expanded state illustrated in FIG. 4B.

With continued reference to FIG. 4B, the non-foreshortening portion 100of the illustrated stent 90 comprises a plurality of rows or rings 114a-c of circumferentially expansible elements, or struts 115, arranged ina zigzag pattern. The struts 115 are configured to expand and contractwith a change in radius of the stent 90. In the illustrated embodiment,the stent has three such rings 114 a-c. It is to be understood that moreor fewer rings can be employed as desired to accomplish the purposes ofthis stent frame. In the illustrated embodiment, the respective ends ofeach circumferential undulating strut 115 joins an adjacent strut 115 atan apex 116, 118 which is, in at least some embodiments, an area ofpreferential bending. In the illustrated embodiment, the zigzag patternof a first 114 a and a third ring 114 c are generally in phase with oneanother, while the struts 115 of a second ring 114 b between the firstand third rings 114 a, 114 b are generally out of phase with those ofthe first and third rings. It is to be understood that, in otherembodiments, all or most of the rings can be in phase with one anotheror out of phase as desired.

With continued reference to FIG. 4B, longitudinal struts 120 extendtransversely across the rings 114 a-c of the non-foreshortening portion100 from the first end 92 of the frame 90 to the transition 112. Moreparticularly, each ring 114 shares a common longitudinal strut 120. Thelongitudinal struts 120 extend through apices 116 of adjacent rings 114,and preferably extend the entire length of the non-foreshorteningportion 100. Preferably, the longitudinal struts 120 comprise anon-expandable rod or bar. The apices 116 that are connected to thelongitudinal struts 120 are referred to as “connected” apices 116.Apices 118 not connected to longitudinal struts 120 are referred to as“free” apices 118.

As noted above, the longitudinal struts 120 are not substantiallyexpandable in a longitudinal direction. As such, even though theundulating struts 115 provide flexibility in radial expansion orcompaction, as the stent 90 changes radial size between the compactedand expanded states, the longitudinal length of the stent in thenon-foreshortening portion 100 remains substantially unchanged. In otherembodiments, the longitudinal struts may include expansible elementsthat may allow the struts to expand somewhat longitudinally. However,such longitudinal expansion would not be directly tied to any change instrut radius.

With continued reference to FIGS. 4A and 4B, the foreshortening portion110 of the illustrated stent frame comprises a first and a secondcircumferential ring 124 a, 124 a that are each made up ofinterconnected cells 130. Each cell 130 comprises a plurality of strutmembers 132 that are interconnected in such a way that when the stentexpands radially, the cell 130 becomes longitudinally shorter. In theillustrated embodiment, each cell 130 is enclosed and is configured ingenerally a diamond-shaped pattern. Circumferential and longitudinalcell connectors 134, 136 connect adjacent cells 130 to one another. Anupper end 140 of each cell 130 in the first ring 124 a is connected to asecond end 142 of a corresponding longitudinal strut 120 of thenon-foreshortening portion 100 at the transition 112.

Although the illustrated foreshortening cells 130 are arranged in adiamond pattern, it is to be understood that other configurations can beemployed. For example, in other embodiments, the foreshortening cellscan be generally oval-shaped, and in further embodiments the cells maynot be fully enclosed. As discussed above and illustrated in FIGS. 4Aand 4B, when the illustrated stent 90 is expanded from the compactedstate to the expanded state, the non-foreshortening portion 100 of thestent remains substantially the same length while the foreshorteningportion 110 of the stent becomes substantially shorter in length.

With continued reference to FIGS. 4A and 4B, a plurality of firstanchors 150 extend from the transition 112 into the foreshorteningportion 110. Preferably, each of the anchors 150 also extends generallyradially outwardly from the stent 90 so that a tip 152 of each firstanchor 150 is spaced from the cells 130. Similarly, a plurality ofsecond anchors 154 extend from the foreshortening cells 130 at oradjacent the second end 94 of the stent frame 90 and extend into theforeshortening portion and radially outwardly from the stent so that atip 156 of each second anchor 154 is spaced from the cells 130. A firstdistance is defined between the tips 152, 156 of opposing first andsecond anchors 150, 154 when the stent 90 is in the compacted state, anda second distance is defined between the tips 152, 156 of opposing firstand second anchors 150, 154 when the stent 90 is in the expanded state.As shown, the second distance is substantially less than the firstdistance. This arrangement enables the foreshortening portion 110, withits anchors 150, 154, to grasp onto tissues so as to hold the stent inplace.

In preferred embodiments, the stent 90 may be deployed into a heartvalve annulus, and positioned when compacted so that the tips 152, 156of the opposing first and second anchors 150, 154 are disposed onopposite sides of the native annulus. As the stent is expanded, theopposing first and second anchors are drawn closer together so as tograsp opposite sides of the native annulus and securely hold the stentin position. As such, the stent can be held securely in position withoutrequiring a substantial radial force against the native annulus.Applicant's U.S. patent application Ser. No. 12/084,586, which waspublished on Aug. 27, 2009 as U.S. Publication No. 2009/0216314,discusses embodiments of foreshortening stents with anchors, and can bereferred to for further discussion of certain aspects of the illustratedstent embodiment. The discussion in the above application concerningstructure and operation of embodiments of a foreshortening stent,particularly a foreshortening stent having anchors, is expresslyincorporated by reference herein.

In the illustrated embodiment, the stent is made of a shape-memoryalloy, specifically nitinol. It is to be understood, however, that othermaterials, including metals, metal alloys and non-metals can be employedas appropriate.

In a preferred embodiment, the stent frame is initially provided as acircular cross-section nitinol tube. The tube is laser cut according toa pattern corresponding to the struts, cells and the like. The cut tubepreferably is electrochemically polished to as to remove rough edges.The cut and polished nitinol tube may be shaped in accordance with adesired manner, such as shaping the anchors to extend radiallyoutwardly, and the nitinol stent frame may be heated-treated to bothestablish the shape memory and to obtain desired elasticity attributes.

With specific reference next to FIG. 5, an embodiment of a replacementheart valve 160 is illustrated in which the valve body 30 of FIGS. 1-3is disposed on the stent frame 90 of FIG. 4. In this embodiment, theskirt portion 40 of the valve body 30 is disposed on the outside of thestent 90 and the leaflet portion 50 is disposed on the inside of thestent 90. The downstream ring 76 and leaflet supports 80 are attached tothe stent 90. Apertures 162 are formed through the skirt 40 asappropriate to accommodate the anchors 150, 154. The anchors 150, 154and corresponding apertures 162 are configured so that when the stent 90is compacted, the anchors still extend through the apertures. Morespecifically, when the stent 90 is compacted and the foreshorteningportion 110 lengthens, the anchors 150, 154 move within thecorresponding apertures 162, but the anchor tips 152, 156 do not exitthe apertures 162.

In one embodiment, during manufacture, the skirt portion 40 is attachedto the stent 90 before any portion of the leaflet portion 50 is attachedto the skirt portion 40. In some embodiments, the skirt portion 40 isfit over the stent 90 prior to folding the leaflet portion 40. In otherembodiments, the stent is slid between the leaflet portion and skirtportion after they are folded. After the stent 90 is sandwiched betweenthe leaflet portion 50 and skirt portion 40, the leaflets 54 areattached to the leaflet supports 80 and the commissural tabs 60 areattached to the downstream ring 76. In some embodiments, suchattachments are made such that at least portions of the valve body canmove relative to the stent while the stent is foreshortening.

In another embodiment, the skirt portion 40 of the valve body 30 isattached to the outside of the stent 90, and the stent and valve bodyare compressed into the compacted state without the leaflet portion 50being folded relative to the skirt portion 40. As such, the leafletportion 50 is not in contact with or directly connected to the stent 50.During a procedure to deploy the replacement valve into a patient, thepartially-completed assembly is advanced into place and the stent isexpanded so that the anchors grasp the patient's native annulus. Theleaflet portion 50 of the valve is then folded over and into the stent90, and is then attached, while in place, to the skirt portion 40.

With reference next to FIGS. 6A-C, another embodiment of a heart valve200 is illustrated in which a stent frame 290 is sandwiched between aninner layer 250 and an outer layer 240 of a valve body 230. In preferredembodiments the valve body 230 is formed of a single piece of tissuewrapped about the stent frame 290 so that the skirt portion 240 is theouter layer and sits on and is attached to the outside of the stent 290.The leaflet portion 250 is the inner layer. It sits within the interiorof the stent 290 and is attached to the skirt portion 240. In theillustrated embodiment, first and second side edges 264, 266 of leaflets254 are tightly sutured to first and second side edges 272, 274,respectively, of leaflet support portions 280. Commissural tabs 260 ofthe leaflet portion 250 are attached to a downstream ring 276 of theskirt portion 240. In this arrangement, the connection between theleaflet portion 250 and the skirt portion 240 securely holds onto thestent 290, but also prevents leaks. Further, the downstream ring 276, towhich the commissural tabs 260 are attached, helps to distribute forcesexerted on the commissural tabs during valve closure.

Stent anchors 250, 254 in the embodiment illustrated in FIGS. 6A-Cextend through aperture 262 in an upstream ring 278 of the valve body230. In the illustrated embodiment, the stent anchors 250, 254 have awidened portion 285 towards their tips 252, 256. As such, duringelongation of a foreshortening portion 210 of the stent 290 in which theanchors 250, 254 are drawn apart from each other, the enlarged portions285 of the anchors help prevent the tissue valve body 230 from slippingoff the anchors or, more specifically, prevent from the anchor tips 252,256 from slipping through their associated apertures 262.

In additional embodiments, a valve body 230, 30 as depicted in FIGS.6A-C or as in FIGS. 1-4 can be mounted to a stent frame that does notforeshorten upon expansion. As in embodiments above, the skirt 40, 240can be disposed on the outside of the stent frame, and the leafletportion 50, 250 is inverted and folded so as to be within the stentframe, but aligned with the skirt portion. The leaflet portion and skirtportion are then sewn together as appropriate so that at least part ofthe stent frame is sandwiched between the portions. Preferably the valvebody material is contiguous at the fold line between the skirt portionand leaflet portion, which is at or adjacent to the upstream end of theheart valve, thus further decreasing the likelihood of paravalvularleaks.

With reference next to FIGS. 7-9A, another embodiment of a valve body330 is depicted. FIG. 7 discloses a flat pattern 332 for cutting flatsource tissue to assemble into the valve body embodiment. Theillustrated valve body pattern 332 has first and second ends 334, 336,and defines a skirt portion 340 and a leaflet portion 350. The leafletportion 350 comprises three leaflets 354, each having a downstreamleaflet edge 362 and opposing first and second leaflet side edges 364,366. An aperture 368 is cut between adjacent leaflets 354 and the cutout tissue removed so as to define the leaflets 354.

Each of the leaflets 354 has a first and a second opposing commissuraltab portion 360, 361. In the illustrated flat pattern 332, thecommissural tab portions 360, 361 of adjacent leaflets 354 are initiallyco-formed as a connection 363 between adjacent leaflets. During cuttingaccording to the flat pattern, this commissural connection 363 betweenadjacent leaflets 354 is cut so as to define the first and secondcommissural tabs 360, 361 of adjacent leaflets, which first and secondcommissural tabs 360, 361 have first and second cut ends 370, 371,respectively. In the illustrated embodiment, a relatively small jog, oroffset 374, is cut between each leaflet side edge 364, 366 and theadjacent commissural tab 360, 361.

With continued reference to FIG. 7, preferably the skirt portion 340 ofthe valve body 330 is substantially contiguous, without significantcut-outs such as the windows of the FIG. 1-4 valve body. The skirt 340has a downstream edge 376, and is connected to the leaflet portion 350at a fold line 352. In the skirt portion 340, the valve pattern's firstand second ends 334, 336 are cut to be diagonal relative to thedownstream edge 376, which preferably is parallel to the fold line 352.In the illustrated embodiment, commissural slits 380 are cut into theskirt portion 340 so as to be generally aligned with the cut edges 370,371 of adjacent first and second commissural tabs 360, 361.

With specific reference next to FIG. 8, the valve body 330 isconstructed by folding the skirt portion 340 relative to the leafletportion 350 along the fold line 352, and securing the diagonal ends 334,336 of the skirt portion 340 together to establish the tubular shape ofthe valve body 330. In this arrangement, an inner surface 382 of theskirt portion 340 faces outer surfaces 384 of the leaflets 354, and aninterior 386 of the valve body 330 is defined by the inner surface 382of the skirt portion 340. Inner surfaces of the first and secondcommissural tab portions 360, 361 of adjacent leaflets 354 are engagedwith one another, and the engaged tabs 360, 361 are passed through thecorresponding commissural slit 380 of the skirt portion 340. Withspecific reference also to FIG. 9A, which is a close-up view taken fromoutside the skirt portion, the engaged first and second commissural tabportions 360, 361 are arranged so that their cut ends 370, 371 arefacing generally radially outwardly and are adjacent the outer surface390 of the skirt portion 340.

The engaged commissural tab portions 360, 361 are connected to oneanother, preferably by sutures 392. In the illustrated embodiment, aslit edge portion 394 immediately surrounding the slit 380 is made toengage the outer surfaces 396 of the commissural tabs 360, 361 so that acut edge 397 of the slit 380 faces radially outwardly as do the cut ends370, 371 of the tabs 360, 361. The slit edge portion 394 and engagedcommissural tabs 360, 361 then are all sewn together as shown in FIG.9A.

In the illustrated embodiment, the inner surface 382 of the skirt 340 inthe slit edge portion 394 engages an outer surface of the tabs 360, 361.In still other embodiments, the engaged commissural tabs 360, 361 arefirst sewn-together on the outside of the skirt 340, and thesewn-together commissural tabs 360, 361 are then sewn onto the tissuesurrounding the slit 380. In another embodiment, the engaged commissuraltabs 360, 361 are not sewn to one another. Instead, each tab is foldedadjacent its cut edge 370, 371 to engage the outer surface 390 of theskirt portion 340 adjacent the slit 380, and is then sewn to the skirt.In another such embodiment the engaged portion of the commissural tabs360, 361 can also be sewn together, or held together by clips or thelike.

With continued reference to FIGS. 7-9A, the first and second leafletside edges 364, 366 are also sewn to the skirt portion 340. As such, agood seal is sewn between the leaflets 354 and the skirt portion 340 soas to prevent any blood leakage therebetween during operation of thevalve. FIGS. 9A and B show first and second seams 398, 399 that attachthe leaflets 354 to the skirt along the first and second leaflet sideedges 364, 366.

The offset 374 between the leaflet side edges 364, 366 and the tabs 360,361 facilitates a clean transition between the tabs, which extendthrough the commissural slit 380, and the leaflet side edges, which aresewn to the inner surface 382 of the skirt portion 340. Preferably theleaflet edge in the offset 374 also engages the skirt.

The valve body 330 can be sewn together in several ways. In anotherembodiment, the commissural slits 380 can be used as a guide duringfolding of the leaflet portion 350 over the skirt portion 340, and theoperator is careful to make sure the leaflets 391 are properly aligned.In another embodiment, prior to forming the valve body into a tube, butafter folding, at least one and preferably at least two of the leaflets354 are sewn onto the skirt 340. Sewing the leaflets onto the skirt whenstill in a flattened state can be more convenient. This method alsoenables reliable placement of the leaflets 354 in the correct positionrelative to the skirt 340, and maintenance of them in a correctplacement during suturing. Also, since at least one of the leaflets isalready sewn securely in place before the valve body 330 is formed intoa tube by connecting the first and second skirt ends 334, 336, thepreviously-connected leaflet or leaflets function as a guide andreference point to assist in proper placement and sewing of theremaining leaflet(s).

Of course, in other embodiments, the valve body 330 can be rolled into atube prior to folding and/or prior to attaching the leaflets 350 to theskirt portion 340. For example, in one embodiment the commissural tabs360, 361 are attached and put in place once the valve body 330 is rolledinto a tube. Once secured in place, the tabs 360, 361 serve as a guideto help maintain the leaflets 354 in a correct position while they areattached to the skirt 340.

In another embodiment, a valve body 330 is provided having a structuresubstantially as in the valve body of FIGS. 7 and 8, except that thecommissural connection 363 between adjacent leaflets 354, which in FIG.7 is cut to form opposing commissural tabs 360, 361, is not cut, butinstead remains as a commissural tab 363 connecting adjacent leaflets354. Such an embodiment can be constructed substantially as describedabove; however, only the commissural tabs 360, 361 at the first andsecond pattern ends 334, 336 have cut edges 370, 371 so as to beconstructed as shown in Figure A.

With specific reference to FIG. 9, in an embodiment having a contiguouscommissural tab 363 between the leaflets 354, each tab 363 preferably isfolded so that inner surfaces of the tab 363 are engaged. The folded tab363 is passed through the corresponding commissural slit 380. Eachfolded commissural tab 363 is sutured to the skirt portion 340,preferably in a manner similar to the embodiments discussed above.

With reference next to FIG. 10, another embodiment of a flat pattern 432for cutting a valve body 430 from a flat source tissue is illustrated.In this embodiment, the valve body 430 is divided into a skirt portion440 and a leaflet portion 450. The leaflet portion 450 comprises threeleaflets 454, each having a curved downstream leaflet edge 462 andcurved first and second side edges 464, 466. Opposing first and secondcommissural tab portions 460, 461 are also defined on each leaflet 454.In the illustrated pattern, the commissural tab portions 460, 461 andside edges 464, 466 are formed by removing tissue between the leaflets454, including between adjacent first and second tab portions ofadjacent leaflets. Three commissural slots 480 are cut through the skirtportion 440 generally corresponding to the placement of the commissuraltabs 460, 461. The slots 480 of the illustrated embodiment are formed bycutting and removing a portion of tissue, as opposed to simply cutting aslit as in some other embodiments. Once cut from source tissue, thevalve body 430 can be constructed in a manner sharing similarities withthe valve body 330 of FIGS. 7-9.

With reference next to FIG. 11, another embodiment of a stent frame 500is illustrated. In the illustrated embodiment, the stent frame 500comprises a non-foreshortening portion 510 and a foreshortening portion520. The non-foreshortening portion 510 comprises three rings 522 a-522c of undulating circumferentially expansible struts 524 that connect toone another at apices 526, 528. Longitudinal struts 530 have first andsecond ends 532, 534, and extend from a first end 538 toward a secondend 539 of the stent 500 but terminate at a transition 540 from thenon-foreshortening portion 510 to the foreshortening portion 520. Theapices that intersect with the longitudinal struts 530 are referred toas “connected” apices 526, and apices between connected apices 526 arereferred to as “free” apices 528.

In the illustrated embodiment, a first ring 522 a is disposed adjacentthe first end 538 of the stent and a second ring 522 b is disposedadjacent the first ring 522 a. A set of first eyelets 544 are formed atthe connected apices 526 of the second ring 522 b. A set of secondeyelets 546 are also formed at the second ends 534 of each longitudinalstrut 530, which in the illustrated embodiment is also the transition540. In a third ring 522 c, the free apices 528 each comprise aprotuberance 550 extending therefrom, which protuberance can also bereferred to as an apical anchor 550. Preferably the struts 524 in thethird ring 522 c are pre-shaped so as to flare radially outwardly whenthe stent frame 500 is in an expanded state as shown in FIG. 11.

With continued reference to FIG. 11, the foreshortening portion 520 ofthe illustrated stent frame 500 comprises a ring 552 of generallydiamond-shaped cells 555 connected to one another at connectors 556. Afirst end 560 of each cell 555 is connected to the non-foreshorteningportion 510 at the second eyelets 546. As in embodiments discussedabove, the foreshortening cells 555 are configured so that as the stentframe 500 is radially compacted, the foreshortening portion 520 of thestent becomes longitudinally longer and, correspondingly, when the stentframe is expanded radially, the foreshortening portion 520 shortens.

A second end 562 of each cell 555 in the foreshortening portion 520 isattached to an anchor 570 that extends generally radially outwardly andtoward the first end 538 of the stent. An anchor eyelet 572 is formed ineach anchor 570, preferably between a base 574 and a tip 576 of eachanchor 570. During operation, and consistent with other embodimentsdiscussed herein, as the stent 500 in a compacted state is placed at anative heart valve annulus, the compacted stent is first arranged sothat the annulus is disposed between the apical anchors 550 and theanchor tips 576. The stent 500 is then allowed to expand, promptingforeshortening, which brings the anchor tips 576 closer to the apicalanchors 500 and grasps the native annulus therebetween. In theillustrated embodiment, the apical anchors 500 are not collinearlyaligned with the end anchors 570.

With additionally reference to FIGS. 12 and 13, an embodiment of areplacement heart valve 600 comprises a valve body 330 as in FIGS. 7-9attached to a stent frame 500 as in FIG. 11. In this embodiment,however, the entire valve body 330 is disposed inside the stent 500.More specifically, and as illustrated in FIG. 12, the skirt portion 340of the valve body 330 is sewn to the first eyelets 544 of the stent. Inthe illustrated embodiment, the fold line 352 of the valve body 330 ishemmed, and certain stitches 606 of a hem seam 610 also engage the firsteyelets 544 in the non-foreshortening portion 510 of the stent 500. Inthis illustrated embodiment, the hemmed fold line 352 becomes anupstream end 612 of the valve body 330.

With continued reference to FIGS. 12 and 13, an elongate tubular portion620 of flexible, longitudinally expandable fabric is attached to thedownstream end 376 of the skirt portion 340 in the illustratedembodiment. More particularly, a first end of the fabric 622 is sewn tothe downstream end 376 of the skirt portion about the circumference ofthe skirt portion by a downstream seam 624. Also, the fabric 620preferably is connected to the outer surface of the skirt 340, and isalso sewn onto the second eyelets 546 of the stent frame 500.Preferably, the fabric 620 is also sewn to the foreshortening cells 555at several points by connector stitches 626.

In the illustrated embodiment, the fabric 620 curves around the secondend 539 of the stent frame 500, generally following the curvature of thedownstream anchors 570. Second end 628 of the fabric portion 620 is sewnto the anchor eyelets 572. Preferably, the flexible fabric 620 issufficiently expandable to move with the foreshortening portion 520 asthe stent 500 moves between the compacted state and the deployed,relaxed expanded state. As such, in the illustrated embodiment, thetissue valve body 330 is confined to the non-foreshortening portion 510of the stent and the flexible fabric 620 spans the foreshorteningportion 520 of the stent. Thus, the tissue valve body 330 is not subjectto longitudinal expansion and contraction with the stent 500.

In the illustrated embodiment, the tissue portion of the valve body 330is sewn directly to the stent frame 500 at only the upstream end 612.The downstream edge 376 of the skirt portion 340 is attached to thefabric 620, which fabric is sewn directly to the stent 500 at the secondeyelets 546 via the downstream seam 624. In another embodiment, the sameseam 624 that connects the fabric 620 to the skirt 340 also connects theskirt 340 to the second eyelets 546.

With continued reference to FIGS. 7-9 and 11-13, the illustratedembodiment of an assembled heart valve 600 comprises two layers oftissue, preferably formed from a single, contiguous piece of tissue. Theleaflet portion 350 of the valve, which includes the leaflets 354, issewn directly only to the skirt portion 340. As such, during valveoperation between open and closed states, the leaflet portion 350, andspecifically the leaflets 354, directly engages only the skirt portion340. In turn, the skirt portion 340 is attached to and interacts withthe stent 500 and other materials such as the downstream fabric portion620.

It is to be understood that, in other embodiments, a portion or all ofwhat has been shown as the fabric portion 620 in the embodimentillustrated in FIGS. 12 and 13 can be replaced by providing a longerskirt portion of the tissue valve portion. It is also to be understoodthat, in additional embodiments, the illustrated valve body 330 can beused with a non-foreshortening stent.

With reference next to FIG. 14, a schematic representation of the heartvalve 600 as discussed above in connection with FIGS. 12 and 13 isdepicted installed in a human heart 750. The heart is shown incross-section, and represents typical anatomy, including a left atrium752 and left ventricle 760. The left ventricle 760 is defined by amuscular wall 762. The left atrium 752 and left ventricle 760communicate with one another through a mitral annulus 770. Also shownschematically in FIG. 14 is a native anterior mitral leaflet 774 havingchordae tendinae 776 that connect a downstream end of the anteriormitral leaflet 774 to the muscle wall 762 of the left ventricle 760. Aleft ventricle outflow tract 778 extends toward the top of the leftventricle 760.

As shown in FIG. 14, the valve 600 of FIGS. 12-13 is disposed so thatthe mitral annulus 770 is grasped between the anchors 570 and apicalanchors 550 in accordance with a method of aligning and deployment ofthe stent 500 discussed previously. As such, all or most of the stent500 extends into the left atrium. The portion of the stent 500 disposedupstream of the annulus 770 can be referred to as being positionedsupra-annularly. The portion generally within the annulus 770 isreferred to as positioned intra-annularly. The portion downstream of theannulus is referred to as being positioned sub-annularly. In theillustrated embodiment, only a part of the foreshortening portion ispositioned intra-annularly or sub-annularly, and the rest of the stent500 is supra-annular.

In the illustrated embodiment, the anterior mitral leaflet 774 has notbeen removed prior to deploying the replacement valve 600. Preferably,the posterior mitral leaflet (not shown) also has not been removed priorto deploying the replacement valve. However, in other embodiments, oneor both of these natural valve leaflets may be removed before deployingthe replacement valve.

With the stent 500 placed mostly supra-annularly within the left atrium752, the stent 500 does not interfere with left ventricle functionduring pumping. More specifically, the stent 500 does not interfere withblood flow from the left ventricle 760 through the outflow tract 778 anddoes not interfere with deformation of the left ventricle 760 as themuscle wall 762 contracts during pumping. In the illustrated embodiment,the valve body 330 is attached to the stent 500 so that the downstreamedges 362 of the valve are generally within the mitral annulus 770. Thisis referred to as intra-annular placement of the valve body 330.

With reference next to FIG. 15, a schematic cross-sectional side viewschematically showing a portion of a stent 500 a and fabric portion 620a of another embodiment. This embodiment is similar to that of FIGS. 12and 13, except that the fabric portion 620 a extends beyond anchoreyelets 572 a and up to anchor tips 576 a. Preferably the fabric 620 ais wrapped about the anchor tips 576 a and secured in place with a seamaround the circumference of the fabric 620 a so as to form a generallycontiguous band at the tips 576 a of the anchors 570 a. As such, eachanchor 570 a will contact the native valve annulus through the fabric620 a.

With reference to FIG. 16A, another embodiment of a heart valve 600 a isshown. The illustrated heart valve 600 a employs a valve body 330 asdiscussed above in connection with FIGS. 7-9 mounted on a stent 500 bthat, for demonstration purposes, is mostly similar to the stent 500 ofFIGS. 11-13. As indicated in FIG. 16A, stent 500 b, being almost thesame as stent 500, includes most of the same structure and uses the samereference numbers. Such structure is described in connection with thediscussion of stent 500 above.

In the illustrated stent 500 b, a plurality of distal eyelets 800 areprovided at the downstream end 539 of the stent 500 b, which is also thesecond end 562 of cells 555 in the foreshortening portion 520 of thestent 500 b. In this embodiment, the valve body 330 is attached to thestent 500 b so that the downstream edge 376 of the skirt portion 340 isconnected to the downstream eyelets 800, such as by sutures. As such,the leaflets 354, and particularly the downstream edges 362 of theleaflets 354, are arranged at, adjacent, or in some embodimentsdownstream of, second end 539 of the stent 500 b.

With continued reference to FIG. 16A, an elongate tubular flexibleportion 810, having opposing first and second ends 812, 814, is attachedto the valve body 330. More specifically, the second end 814 of theflexible portion 810 is attached to the upstream end 352 of the skirt340, preferably with a circumferential stitch 818. The first end 812 ofthe flexible portion 810 is attached to the stent 500 b at the firsteyelets 544. Preferably, the upstream end 352 of the valve body 330 isnot directly attached to the stent 500 b, but is only attached to theflexible portion 810, which in turn is attached to the stent 500 b.

Preferably the flexible portion 810 is constructed of a flexiblematerial that can increase and decrease in length as the length of thestent 500 b increases and decreases due to foreshortening during radialcompaction and expansion. Also, preferably the valve body 330 isconstructed of a material such as pericardium, which is flexible yet notsubstantially longitudinally stretchable. To the extent the valve bodyis made with a material that stretches, preferably the flexible portion810 is more amenable to longitudinal stretching than the valve body 330so that as the length of the stent 500 b increases, the flexible portion810, rather than the valve body 330, will stretch longitudinally, andvice versa.

With additional reference to FIG. 16B, it is noted that in theillustrated embodiment, a portion of the valve body 330 spans theforeshortening portion 520 of the stent. The longitudinally stretchableflexible portion 810, however, is disposed in the non-foreshorteningportion 510 of the stent 500 b. As the assembled valve 600 a iscompacted from the expanded portion shown in FIG. 16A to the compactedstate shown in FIG. 16B, the foreshortening portion 500 becomes longer.Since the valve body 330 does not stretch substantially, and instead theflexible portion 810 stretches substantially during such lengthening,the stent 500 b moves longitudinally relative to the valve body 330.Such a “floating valve body” configuration enables placement of thevalve body over at least a portion of the foreshortening portion 520 ofthe stent 500 b without stretching the valve body during lengthening ofthe foreshortening portion of the valve during the compaction andexpansion process.

In the embodiment illustrated in FIGS. 16A and B, at least part of theskirt 340, preferably at or adjacent the upstream end, is looselyattached to one or more longitudinal struts 530 of the stent 500 b in amanner that accommodates the floating, longitudinal movement of thevalve body 330 relative to the stent 500 b upon compaction andexpansion, such as by one or more loose stitches 820. In otherembodiments, such loose stitches 820 can be in the flexible portionadjacent the valve body. Preferably the stitches 820 are relativelyloose so that as the stent 500 b moves between the compacted andexpanded states, each stitch 820 slides longitudinally over thecorresponding longitudinal strut 530. Such stitches 820 arestrategically placed so that there is an undisturbed path for the stitchto slide upon.

In the illustrated embodiment, the flexible portion 810 is constructedof a fabric having a sufficiently loose weave and/or material thataccommodates longitudinal stretching during compaction, and also takesup the slack as the stent shortens during expansion. It is to beunderstood, however, that other types of materials and configurationscan be employed for the flexible portion. For example, in anotherembodiment, an elongate tubular portion of pericardium makes up theflexible portion. In this embodiment, preferably the pericardium iscreased so as to preferentially fold, accordion style, as the stentshortens during expansion. In another embodiment, the flexible portioncomprises a pericardium segment having several fenestrations, which arestrategically placed slits that, upon application of longitudinaltension to the pericardium, deform so as to enable the pericardiumsegment to stretch longitudinally. However, as the stent is expanded andforeshortens, the pericardium recovers to its original shape. After thevalve is deployed, and as time passes, tissue in-growth will help toclose the fenestrations. In still other embodiments, yet additionalstructures can be employed. For example, rather than a tubular flexibleportion, the flexible portion can comprise an array of elastic cordsthat attach to the upstream end of the valve body 330, extendlongitudinally upon compaction of the valve, and take up the slack asthe valve is expanded. Also, although the illustrated embodimentemployed the valve body 330, which has two layers, it is to beunderstood that other embodiments may employ a single-layer valveconnected to a flexible portion and mounted on a stent having aforeshortening portion.

With reference next to FIG. 17, a schematic representation is made ofthe valve 600 a of FIGS. 16A and B mounted in a human heart. In theillustrated embodiment, the stent 500 b is mounted in a mannersubstantially similar to the stent 500 depicted in FIG. 14. However, thevalve body 330 is positioned farther downstream relative to the stent sothat the leaflets 354 are generally within the mitral annulus 770, whichposition can be referred to as intra-annular or partially intra-annular,as the downstream edges 362 of the leaflets 354 may be downstream of theannulus, and thus sub-annular. It is to be understood that, in otherembodiments, a valve body can be mounted relative to the stent to beentirely supra-annular, intra-annular, sub-annular, or combinationsthereof.

With reference next to FIGS. 18 and 19, yet another embodiment of avalve body 630 is illustrated. FIG. 18 shows a flat pattern 632 forcutting the valve body 630 out of flat source tissue. As shown, thepattern 632 comprises a skirt portion 640 and a leaflet portion 650. Theleaflet portion 640 comprises three leaflets 654 each having adownstream edge 662 and opposing first and second side edges 664, 666.Each leaflet 654 has opposing first and second commissural tab portions660, 661. An offset 674 is provided between each leaflet side edge 664,666 and the adjacent commissural tab 660, 661.

In the skirt portion 640, three commissural slits 680 are cut so as togenerally align with the commissural tabs 660, 661. First and secondleaflet edge slits 694, 696 are also cut in the skirt portion 640 so asto generally align with the curvature of the corresponding first andsecond leaflet side edges 664, 666. In the illustrated embodiment, aportion 700 of each commissural tab 660, 661 extends in the downstreamdirection beyond at least a portion of the leaflet downstream edge 662.

With continued reference to FIGS. 18 and 19, to construct the valve body630 from flat tissue cut according to this pattern 632, the cut tissueis folded and the first and second leaflet edges 664, 666 are pushedthrough corresponding first and second leaflet slits 694, 696,respectively. Edges of the skirt portion 640 at and adjacent the leafletslits 694, 696 preferably are deformed so that the inner surface of theskirt 640 at and adjacent the slits 694, 696 engages inner and outersurfaces of the leaflet 654 so that a leaflet cut end 704 and opposingslit cut ends 706, 708 face radially outwardly. The leaflet cut end 704and slit cut ends 706, 708 are then sutured together. As such, thesutures connecting the leaflet edges 664, 666 to the skirt 640 aremaintained generally on the outside 703 of the skirt portion 640, andportions of the leaflets 654 within the valve body 630 generally do notengage the sutures during use. Similarly, and in the manner as discussedin other embodiments, the first and second commissural tab portions 660,661 of adjacent leaflets 654 are arranged to engage one anotherface-to-face, extended through the slit 680, and sewn to each other andthe skirt 640 at the slit edge.

In still other embodiments, the leaflet side edges 664, 666 can beextended through corresponding slits 694, 696, folded to engage with theouter surface 703 of the skirt portion 640, and then sutured into place.

In the illustrated embodiment, the downstream portion 700 of thecommissural tab portions 660, 661 contributes to surface area for sewingthe commissural tab portions in place and provides material to hold ontoduring the manufacturing process. In some embodiments, the entirecommissural tab 660, 661 is sewn to the skirt 640. In other embodiments,a portion of the tabs are sewn in place, and an unused remainder of eachtab is removed and discarded.

With reference next to FIG. 20, a tool 830 for helping to construct thevalve body 630 of FIGS. 18 and 19 is illustrated. The tool 830 has aproximal handle portion 832 and a form 840, or mold, at its distal end.Preferably, the form 840 is shaped to be the negative of a desired shapeof the downstream portion of the valve body 630 when the leaflets 654are coapted in a closed position. The illustrated form 840 comprises astop surface 844 and a plurality of leaflet engagement surfaces 850,each of which have first and second side edges 854, 856.

With additional reference to FIG. 21, the tool 830 is shown duringconstruction of a valve body 630. In a preferred embodiment, the valvebody 630 is cut according to the pattern 632 discussed above, and isthen formed into a tube and connected at the commissural tabs 660, 661.Preferably, the commissural tabs 660, 661 are initially only tacked inplace, and thus serve as a guide for placement of the partiallyassembled valve body 630 on the form 840. The downstream end of thepartially assembled valve body 630, is then placed upon the form 840 sothat the skirt 640 engages a circumferential outer surface 860 of theform, and the leaflets 654 engage corresponding leaflet engagementsurfaces 850 and the first and second side edges 664, 666 of theleaflets 654 are generally aligned with the first and second side edges854, 856 of the leaflet engagement surfaces 850. Preferably, downstreamedges 662 of the leaflets 654 are at or adjacent the stop surface 844 ofthe form 850.

In a preferred embodiment, the operator correctly positions the valvebody 630 on the form 840 and pulls side edges 664, 666 of the leaflets654 through the corresponding leaflet slits 694, 696 of the skirtportion 640, all of which are preferably aligned with the leafletengagement surface side edges 854, 856. In this manner, thepartially-assembled valve body 630 becomes engaged with the form 840,taking on the form's shape so that the leaflets are configured in thepreferred coapted position. As such, the valve body 630 can beconstructed in a position that is exactly as desired for optimum valveperformance. Once the valve body 630 has been properly positioned on theform 840 with the leaflet edges 664, 666 pulled through correspondingleaflet slits 694, 696, the leaflet edges 664, 666 are sewn or otherwiseattached to the valve body 630 along the slits 694, 696 in anyacceptable manner, including methods as discussed above. Additionally,in embodiments in which the commissural tabs were initially only tackedin place, they are then fully secured in place.

Use of the valve assembly tool 830 as discussed above enables consistentand ideal-shaped construction of a valve body in a relatively quickmanner. In one embodiment, a method of creating a homologous tissuevalve body is provided in which a clinician harvests a patient's owntissue, such as a patient's own pericardium, flattens the homologoussource tissue, cuts it according to a desired heart valve pattern, andthen assembles the valve body using the valve body assembly tool 830.Preferably, the valve can be created and then implanted by a clinicianin the operating room during a single procedure.

With reference next to FIG. 23, another embodiment of a valve body 930can be formed generally using much of the same pattern and manner ofconstruction as discussed above in connection with FIGS. 7-9, with theexception that a plurality of chordae tendinae 932, 934 extend from thedownstream edge 362 of each leaflet 354. In the illustrated embodiment,a central and two side chordae 932, 934 are provided. Preferably thecentral chordae 932 is longer than the side chordae 934. In otherembodiments, more or fewer chordae may be provided. In the illustratedembodiment, the chordae 932, 934 are cut as part of the pattern, andthus are contiguous with the associated leaflet 354. Preferably a mounttab 936 is at the tip of each chord 932, 934. The mount tab 936preferably includes an area of increased diameter that will providespace to accommodate mounting media 938 such as sutures, clips or thelike.

FIG. 23 is a schematic representation of a replacement valve 900employing the valve body 930 attached to a stent 902. Preferably thechordae 932, 934 are attached to the stent 902 downstream of the valvebody which, in FIG. 23, is depicted in a closed state. As with naturalchordae, preferably the chordae 932, 934 are long enough to allow theleaflets 354 to coapt fully with little or no interference, but alsoprovide distribution of blood pressure forces during pumping of theventricle. More simply, the chordae communicate blood pressure forces onthe leaflets to the frame 902.

With additional reference to FIG. 24, a portion of the stent 902 thatcan be used to support the valve body 930 and chordae 932, 934 isprovided. The illustrated stent is similar to the stent 500 describedabove. Preferably, a plurality of distal eyelets 940 is formed at oradjacent a distal end 539 of the stent. In the illustrated embodiment,the distal eyelets 940 each have a transversely elongate hole 942 with agenerally flat contact surface 944. An attachment eyelet 950 is disposedon the longitudinal struts 530, preferably on the ring 522 c thatincludes the apical anchors 550.

With specific reference to FIG. 25, a schematic representation is showndepicting a portion of the valve body 930, stent 902 and chordae 932,all in section. As shown, preferably a downstream end of the valve bodyis attached via sutures to the second eyelets 546 similar to embodimentsdiscussed above. The valve body leaflets 354 are shown schematically, inphantom lines, and in a coapted state. In the illustrated embodiment,the chordae 932 extends from the leaflet and through the downstreameyelet 940. In some embodiments, the chordae can be sewn to thedownstream eyelet 940. However, in the illustrated embodiment, thechordae extends through the eyelet, engages the contact surface 944,reverses course, and extends to the attachment eyelet 950. Preferably,the mount tab 936 of the chordae 932 is attached to the attachmenteyelet 950 with, for example, a suture 938. In this manner, as forcesfrom blood pressure push against the coapted leaflets of the closedvalve, the chordae distribute such forces to the downstream end of theforeshortening portion of the stent and also to the upstream end of theforeshortening portion of the stent, not only distributing forces fromthe leaflets, but also encouraging the stent anchors 550, 570 into evenmore firm and secure grasping of the native valve annulus. Of course, itis to be understood that other specific areas of attachment of thechordae can be employed.

Although this invention has been disclosed in the context of certainpreferred embodiments and examples, it will be understood by thoseskilled in the art that the present invention extends beyond thespecifically disclosed embodiments to other alternative embodimentsand/or uses of the invention and obvious modifications and equivalentsthereof. In addition, while a number of variations of the invention havebeen shown and described in detail, other modifications, which arewithin the scope of this invention, will be readily apparent to those ofskill in the art based upon this disclosure. In fact, the embodimentsspecifically disclosed herein have been used as a vehicle to describecertain inventive features that could be employed in multipleembodiments. Thus, it is contemplated that various combinations orsubcombinations of the specific features and aspects of the embodimentsmay be made and still fall within the scope of the invention. Forexample, the valve body of FIGS. 7-9 has been described in an embodimentin which adjacent commissural tabs are cut (see FIG. 9A) and in anotherembodiment in which commissural connections between leaflets are not cut(see FIG. 9B). However, the discussion connected with the valve bodyembodiment in FIG. 10 does not specifically describe an embodiment inwhich the commissural connections between leaflets are not cut. SinceApplicant contemplates combining and/or substituting features of thediscussed embodiments, it should be understood that Applicant alsocontemplates a variation of the FIG. 10 valve body which employs uncutcommissural connections. This example applies to all of the featuresdescribed herein in connection with specific embodiments. Accordingly,it should be understood that various features and aspects of thedisclosed embodiments can be combined with or substituted for oneanother in order to form varying modes of the disclosed invention. Thus,it is intended that the scope of the present invention herein disclosedshould not be limited by the particular disclosed embodiments describedabove, but should be determined only by a fair reading of the claimsthat follow.

What is claimed is:
 1. A prosthesis configured to be deployed within anative valve, the prosthesis comprising: an expandable frame comprisinga proximal end, a distal end and a longitudinal axis extending betweenthe proximal and distal ends, the frame comprising a foreshorteningportion having a plurality of foreshortening cells, the frame configuredto radially expand and collapse for deployment within the native valve;a number of proximal anchors each connected to the frame and having freeends positioned radially outward from the frame when the frame is in anexpanded configuration, wherein each of the plurality of proximalanchors comprises first and second struts connected to and extendingradially outward from the frame when the frame is in an expandedconfiguration; a number of distal anchors equal to the number ofproximal anchors, the distal anchors each connected to the frame andhaving free ends positioned radially outward from the frame andextending toward the proximal end when the frame is in an expandedconfiguration; a valve body attached to the frame, wherein the valvebody can move between (i) an open position wherein blood can flow fromthe proximal end toward the distal end; and (ii) a closed position whichblocks blood from flowing from the distal end toward the proximal end;wherein the frame is configured such that radial expansion of the framecauses the free ends of the proximal and distal anchors to draw closertogether; and wherein the prosthesis is configured such that, after theprosthesis has been delivered to the native valve and expanded, theproximal anchors are positioned on an inflow side of the native valveand the distal anchors are positioned on an outflow side of the nativevalve.
 2. The prosthesis of claim 1, wherein when the frame is in anexpanded configuration, the free ends of the proximal anchors areequally spaced around an entire circumference of the frame.
 3. Theprosthesis of claim 2, wherein when the frame is in the expandedconfiguration, the free ends of the distal anchors are equally spacedaround the entire circumference of the frame.
 4. The prosthesis of claim3, wherein the free ends of the proximal anchors and the distal anchorsare circumferentially offset when the frame is in an expandedconfiguration.
 5. The prosthesis of claim 1, wherein a distance betweenthe first and second struts where the first and second struts connect tothe frame is greater than a distance between the first and second strutsnear the free end of each proximal anchor.
 6. The prosthesis of claim 5,wherein the first and second struts form a V-shape.
 7. The prosthesis ofclaim 1, wherein the foreshortening portion comprises a row offoreshortening cells and wherein the number of proximal anchors and thenumber of distal anchors is the same as the number of foreshorteningcells in the row.
 8. The prosthesis of claim 1, wherein each of thedistal anchors is connected to a distal portion of a foreshorteningcell.
 9. The prosthesis of claim 8, wherein each of the distal anchorsis connected to a distal apex of a foreshortening cell.
 10. Theprosthesis of claim 1, wherein the first and second struts are eachconnected to the frame at a connection point and wherein a distancebetween the connection points of the first and second struts isapproximately equal to a distance between two lateral sides of at leastone of the foreshortening cells.
 11. The prosthesis of claim 1, whereineach of the distal anchors comprises a straight segment.
 12. Theprosthesis of claim 1, further comprising a skirt extending over atleast one of the plurality of proximal anchors and the plurality ofdistal anchors.
 13. The prosthesis of claim 1, comprising at least nineproximal anchors and at least nine distal anchors.
 14. The prosthesis ofclaim 1, comprising twelve proximal anchors and twelve distal anchors.15. A prosthesis configured to be deployed within a patient's mitralvalve having a mitral annulus, the prosthesis comprising: an expandableframe comprising a proximal end, a distal end, and a longitudinal axisextending between the proximal and distal ends, the frame configured toradially expand and collapse for deployment within the mitral valve, theframe comprising a foreshortening section having a row of foreshorteningcells near the distal end of the frame; a number of distal anchors eachhaving a base connected to a distal portion of a foreshortening cell,the distal anchors each having free ends positioned radially outwardfrom the frame and extending toward the proximal end when the frame isin an expanded configuration so that the free ends of the distal anchorsare closer to the proximal end than the bases are to the proximal end;and a number of equally spaced proximal anchors proximal to the distalanchors and positioned around an entire circumference of the frame, eachproximal anchor having a free end which is positioned radially outwardfrom the frame when the frame is in an expanded configuration; a valvebody attached to the frame, wherein the valve body can move between (i)an open position wherein blood can flow from the proximal end toward thedistal end to allow blood to flow from the left atrium to the leftventricle; and (ii) a closed position which blocks blood from flowingfrom the distal end toward the proximal end to block blood from flowingfrom the left ventricle to the left atrium; wherein the free ends of theproximal anchors and the free ends of the distal anchors arecircumferentially offset when the frame is in an expanded configuration;wherein the prosthesis is configured such that, after the prosthesis hasbeen delivered to the mitral valve and expanded, the proximal anchorsare on an atrial side of the mitral annulus and the distal anchors areon a ventricular side of the mitral annulus; and wherein the frame isconfigured such that radial expansion of the frame causes the free endsof the proximal anchors and the free ends of the distal anchors to drawcloser together.
 16. The prosthesis of claim 15, wherein each of theproximal anchors comprises first and second struts and a distancebetween the first and second struts decreases towards the free end ofthe proximal anchor.
 17. The prosthesis of claim 16, wherein the firstand second struts are each connected to the frame at a connection pointand wherein a distance between the connection points of the first andsecond struts is approximately equal to a distance between two lateralsides of at least one of the foreshortening cell.
 18. The prosthesis ofclaim 17, wherein the first and second struts form a V-shape.
 19. Theprosthesis of claim 15, wherein the number of distal anchors is the sameas the number of foreshortening cells in the row.
 20. The prosthesis ofclaim 15, wherein the number of proximal anchors is the same as thenumber of foreshortening cells in the row.
 21. The prosthesis of claim15, wherein each of the distal anchors comprises a straight segment. 22.The prosthesis of claim 15, wherein the prosthesis has the same numberof the proximal and distal anchors.
 23. The prosthesis of claim 15,further comprising a skirt extending over at least one of the pluralityof proximal anchors and the plurality of distal anchors.
 24. Theprosthesis of claim 15, comprising at least nine proximal anchors and atleast nine distal anchors.
 25. The prosthesis of claim 15, comprisingtwelve proximal anchors and twelve distal anchors.